Dinoseb (2-sec-butyl-4,6-dinitrophenol) is a phenolic herbicide used on soybeans, vegetables, fruits and nuts, citrus,
and other field crops for the selective control of grass and broadleaf weeds. It is also used as an insecticide in grapes,
and as a seed crop drying agent. In 1986 dinoseb was banned as a commercially available product in the U.S. because
of the potential risk of birth defects and other adverse health effects for applicators and other persons with substantial
dinoseb exposure. In addition, EPA has established a maximum contaminant level (MCL) for dinoseb in groundwater
of 7 ug/L.
At an agricultural chemical distribution facility in Oregon, groundwater was monitored for various herbicides
including dinoseb. Historical concentrations had exceeded 25,000 ug/L and monitored natural attenuation (MNA) was
not sufficient to reach cleanup goals. Dicamba, another herbicide, was also present in smaller concentrations. A field
scale pilot test using HRC was implemented and results showed reducing trends of dinoseb. Reductions in dicamba
were also seen as microbial activity began to increase. The pilot test was centered around well MW-1 while
downgradient well MW-5 was installed just prior to injection.